1. Technical Field
This disclosure relates to a recording method for an optical recording medium, a recording medium, and a recording apparatus. The present invention particularly relates to an optical recording and reproducing method for a dye-based recordable DVD, a dye-based recordable optical recording medium and a recording apparatus suitably used for the optical recording and reproducing method.
2. Description of the Related Art
At the present day, developments on speeding up of performance of DVDs±R are more advanced as high-capacity optical discs. To further increase recording capacity of optical discs, as elemental technologies, there are various needs for developments of recording materials to make recording pits microscopic, adoption of image compression technologies typified by MPEG2, and shortening of wavelengths of semiconductor laser for reading recording pits.
For semiconductor lasers in the red wavelength region, only AlGaInP laser diodes having a wavelength of 670 nm have been commoditized for bar code readers or measuring instruments so far, however, along with high-densification of optical discs, red lasers have become to be fully used in the optical storage market. For light sources for DVD drives, laser diodes are standardized with two wavelength bands, i.e., with the 635 nm wavelength band and the 650 nm wavelength band. In contrast, reproducing-only DVD-ROM drives are commoditized with the 650 nm wavelength band.
Typically, for dye-based recordable DVD media in which pits (recording marks) are formed according to heat mode, the pulse width and the recording power of a recording pulse (train) formed by laser light emission at the time of recording are optimized at a specific recording speed, and the states of marks and spaces which are formed at different recording linear speeds vary. Namely, the jitter property degrades due to insufficiency in the heat capacity arising due to the leading heating pulse needed for mark formation, dispersion in the average lengths of marks due to different heating temperatures reached with respect to the optimal decomposition temperature, uniform mark widths being unable to be obtained due to the duty ratios of the optimal heating pulses being different, and the occurrence of thickening or thinning in accordance with the mark lengths.
With a background of these circumstances, for DVDs+R, for example, emission waveforms of recording pulses are described, for example, in DVD+R 4.7 Bytes Basic Format Specifications Ver. 1.3 and in DVD+R 8.5 Bytes Basic Format Specifications Ver. 1.0). The former is written standards for single layer 16× DVD+R media, and the latter is written standards for two-layered 2.4× DVD+R media.
However, particularly when information is recorded on a two-layered recording medium at a recording speed of 2.4× or more, with the emission waveforms of recording pulses described in the above-noted standards, sufficient quality may not be obtained depending on the used recording medium.
Further, with respect to the physical formats of DVD media, in the case of the format of a DVD-R medium, it is standardized in a format in which a portion of a land portion called a land prepit is cut. When this format is adopted, at a land prepit signal (LPPb) of less than 0.16, prepit information such as the prepit address and the like cannot be reproduced well, and when it exceeds 0.32, the LPP signal itself exhibits noise-like behavior in the data region, and many data errors arise. Accordingly, for the LPP, a cut width which suits the recording medium is finely-adjusted using a stamper, and the land cut width must be controlled such that LPPb is in a range of 0.16 to 0.32.
As for optical recording media using dyes for their recording layers, there are various optical recording media such as those using polymethine dyes or polymethine dyes and light stabilizing materials as their recording materials; those having a recording layer having a layer containing a tetraazaporphyrin (porphyradine) dye or a layer containing a cyanine dye +an azo metal chelate dye (salifiable dye), and a reflective layer; those using a formazan (metal chelate) dye +other dyes for the recording materials; and those using dipyrromethene (metal chelate) dyes+other dyes for the recording materials. Further, there are a number of known optical recording media using dyes for their recording materials to perform multi-pulse recording, however, as far as the present inventors know, there is no document found that information is recorded on a dye-based recordable DVD medium by the use of one pulse beam and recording waveforms formed at the time of recording at high-linear velocity are focused on, as can be seen in the recording method for a dye-based recordable optical recording medium of the present invention.
However, there are recording methods using one pulse beam for one rectangular waveform or one mark (for example, Japanese Patent Application Laid Open (JP-A) Nos. 2001-243626, 2002-063721, 2001-273636, 2002-298415, 2001-176073, and 2001-155339, and U.S. Pat. No. 4,646,103.